The present inventions relate to improvements in topical compositions and methods for the treatment and prevention of pseudofolliculitis barbae and ingrown hair.
Pseudofolliculitis barbae is the clinical name given to the condition commonly known as "razor bumps." Generally, this condition is described as the ingrowth of emerged hairs back into the skin at a location adjacent to the follicle from which the hair has emerged. This penetration back into the skin causes an antigenic foreign body reaction at the point of penetration, resulting in lesions consisting of firm papules and pustules in which the ingrown hair can become buried. Infections can become superimposed upon this basic state, augmenting the inflammatory reaction. Thus, further shaving becomes difficult and painful.
Pseudofolliculitis barbae is caused by shaving strong and highly curved hairs. For this reason, the condition tends to have a greater incidence in the bearded areas of males of the Negro race. However, it also affects other races, and ingrown hairs can be a problem for other shaved areas such as the underarms and legs. These curved hairs, instead of emerging straight from the hair follicle and the surface of the skin, tend to emerge oriented parallel to the skin surface and, owing to their curvature, are mechanically biased toward re-entry into the skin. Because these hairs are curved, they often are not closely cut at their point of emergence during shaving. In practice, shaving serves to obliquely cut the biased hair rather than cut across the cross-section of the hair, leaving a relatively sharp point at the tips that facilitates skin penetration. Before the next shave, the point or tip of the hair grows into the skin, bringing about the reaction and condition of pseudofolliculitis barbae.
As may be appreciated, total abstinence from shaving is not, for the most part, a practical solution to the problem. Short of abstinence from shaving, however, prevention of pseudofolliculitis barbae has proven difficult. In theory, frequent shaving to cut emerging hairs closer to the skin surface should eliminate the condition by regularly removing the hairs before they grow and re-enter the skin. In practice, however, shaving frequently enough and close enough to skin level to avoid the condition is difficult
Some efforts to cut facial hair at the skin level have involved stretching the skin, which actually results in the cutting of the hairs below the skin level. This can result in an intra-follicular ingrown hair in which the sharp tip of the curved hair, instead of emerging from the follicle, penetrates the follicle wall to bring about the same or similar foreign body reaction as would occur when a hair normally emerges from the follicle but then re-enters the skin.
The use of depilatory compositions has been suggested for the prevention of pseudofolliculitis barbae and ingrown hair. For some persons, this can be effective in achieving the non-cutting removal of the hairs before they can re-enter the skin. However, for others, the depilatory itself can be an irritant and cause a dermatological reaction. Also suggested have been compositions that soften the facial hair to inhibit their ability to penetrate the skin. However, most of these compositions bring about skin irritations or other dermatological side effects when used with the necessary frequency to present a regularly clean-shaven appearance.
Prior art known to the inventors concerning the subject of pseudofolliculitis barbae includes the following references: U.S. Pat. No. 3,981,681 issued to Mario de la Guarida on Sep. 21, 1976; U.S. Pat. No. 4,228,163 issued to William E. Bliss on Oct. 14, 1980; U.S. Pat. No. 4,525,344 issued to Ronald J. Tutsky on Jun. 25, 1985; U.S. Pat. No. 4,775,530 issued to Nicholas V. Perricone on Oct. 4, 1988; and U.S. Pat. No. 5,034,221 issued to Steven E. Rosen et al. on Jul. 23, 1991. In particular, U.S. Pat. No. 5,034,221 (the '291 patent) discloses a treatment for pseudofolliculitis barbae involving the topical application to the beard areas of the face a composition consisting essentially of acetylsalicylic acid, corn starch, isopropyl alcohol, and aloe vera. The '221 patent teaches the advantages of the composition including corn starch and aloe vera gel. Although the invention disclosed in the '221 patent is helpful in the treatment of the condition, improvements and different advantages are desirable in the treatment of pseudofolliculitis barbae.
Also known to the inventors herein are U.S. Pat. No. 4,219,548 issued to Herbert H. Reller on Aug. 26, 1980; U.S. Pat. No. 4,364,940 issued to Edward S. Neiss et al. on Dec. 21, 1982; and U.S. Pat. No. 4,665,063 issued to Daniel Bar-Shalom on May 12, 1987. These references are nonanalogous to the present invention because they primarily relate to the treatment of acne. It may be appreciated that the cause and nature of acne differs materially from pseudofolliculitis barbae and ingrown hair. Acne is an inflammatory condition involving the sebaceous or oil glands of the skin, most commonly the skin of the face. The causes and condition of acne are unrelated to the causes and condition of pseudofolliculitis barbae and ingrown hair.
U.S. Pat. No. 4,665,063 (the Bar-Shalom patent) also relates to the treatment of psoriasis and seborrhea. Although the causes of these noninfectious dermatological disorders are not known to the inventors, psoriasis and seborrhea are both characterized by crusting and flaking lesions of the skin, which symptoms do not occur in infectious pseudofolliculitis barbae. Furthermore, psoriasis and seborrhea commonly affect skin other than that of the face. Thus, it appears that whatever the causes of these other conditions, they are totally unrelated to the known causes of pseudofolliculitis barbae and ingrown hair.
The Bar-Shalom patent suggests in general terms the use of acetylsalicylic acid at a concentration of at least 11% by weight in a suitable "carrier" for the treatment of dermatological disorders such as acne, psoriasis, and seborrhea. Furthermore, the patent states that "[w]hile physiologically acceptable and compatible carriers for the acetyl salicylic acid include liquid paraffin, lanolin, white soft paraffin, white bees wax, and certain alcohols such as propanol, isopropyl alcohol, glycerol and glycol, along with mixtures of any thereof, the especially-preferred carrier for the acetyl salicylic acid is ethanol alone, with the acetyl salicylic acid being present in the ethanol in the amount of 11% by weight to saturation" (which is about 12.5-13% by weight in ethanol). Thus, the Bar-Shalom patent suggests that other than the especially-preferred carrier of ethanol alone, any one or more of the multitude of listed carriers is acceptable and combinations of such carriers may be used in any proportions. Several of these ingredients are unsuitable for the treatment of pseudofolliculitis barbae and ingrown hair and are irritating to the delicate facial skin, particularly at high concentrations, however, the Bar-Shalom patent makes no distinction among them.